JPH11282308A - Heating device and image forming device provided with the heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely attain compatibility of reduction of temperature ripple in a maintaining process and overshoot in a heating process by adopting control values different from each other for control tables for PID control in the heating and maintaining processes. SOLUTION: Electric power according to the detected temperature of a thermister 18 before starting a heater 15 and the rate of change of the detected temperature of the thermister 18 and the like is supplied from a commercial power source to the heater 15. Because a CPU controls the power supply based on a control table, accompanying temperature rise of the heater 15 to a specified temperature, a heating process raising the temperature of the heater 15 to a target temperature is performed. When the heater 15 reaches the target temperature, for maintaining the target temperature, the CPU controls the power supply based on a control table to perform a maintaining process of the target temperature. the control table for PID control in the heating and maintaining processes, adopt control values different from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for performing a heating process on a recording medium carrying an unfixed image or a fixed image, and an image forming apparatus provided with the heating device.

[0002]

2. Description of the Related Art In general, a heating device is a fixing device for fixing an unfixed image carried on a recording medium to the recording medium,
It has been put to practical use as a hypothetical attachment device for temporarily fixing the unfixed image on the recording medium and a surface modifying device for modifying the surface properties of the recording medium carrying the fixed image.

As a fixing device, a nip portion formed between an endless belt-shaped film as a fixing member and a cylindrical pressing roller as a pressing member is pressed against a sheet-shaped recording medium carrying an unfixed image. An apparatus in which a fixing process is performed on the recording medium by heating of a heating unit while passing the paper through the paper is known and is in practical use.

As a method for controlling the temperature of the heating means, conventionally, JP-A-63-313182 and JP-A-2-157.
No. 878 and the like (hereinafter, referred to as a conventional temperature control method) are known, and a predetermined control table and a temperature detected by a temperature detector provided in a heating unit are provided. Is controlled by controlling the power supply from the commercial power supply to the heater based on the comparison result.

[0005] That is, conventionally, a heating step in which a heating means is started up to a predetermined temperature which is lower than a target temperature for heat treatment, and then the heating means is heated from the predetermined temperature to the target temperature. And power supply from the commercial power supply to the heating means in each step of maintaining the heating means to the target temperature,
By performing the PID control based on the detected temperature of the temperature detector and the comparison result of one predetermined control table, the temperature control of the heating means in each of the steps has been performed.

[0006]

By the way, in the heating step, in order to speed up the heating of the heating means to the target temperature, the setting of the control value in the control table is somewhat rough and sufficient. On the other hand, in the maintenance step, the control values in the control table need to be taken to some extent in order to stabilize the heating means to the target temperature.

However, in the conventional temperature control method, the power supply from the commercial power supply to the heating means in each of the temperature raising step and the maintenance step is performed based on one predetermined control table. From this, an improvement in compatibility of the temperature control of the heating means in both the temperature raising step and the maintenance step has been left.

That is, in the conventional temperature control method, when the control section width is determined based on the temperature controllability of the heating means in the temperature raising step, the temperature controllability of the heating means in the maintenance step is reduced. Since the control values in the control table are too rough, it becomes difficult to reduce the temperature ripple of the heating means in the maintenance process.

In the conventional temperature control method, when the control section width is determined with reference to the temperature control of the heating means in the maintenance step, a control table for the temperature control of the heating means in the temperature raising step is used. Is too fine, it is difficult to reduce the overshoot of the heating means in the temperature raising step.

Therefore, in the conventional temperature control method, it has been difficult to achieve both the temperature ripple in the maintenance process and the overshoot in the temperature raising process.

Accordingly, an object of the present invention is to provide a heating device or an image forming apparatus provided with the heating device, which can surely achieve both a temperature ripple in a maintenance process and a reduction in overshoot in a temperature raising process. And

[0012]

According to the present invention, an object of the present invention is to provide a recording medium carrying an unfixed image or a fixed image, and a nip formed between a fixing member and a pressing member pressed against each other. A heating device that performs heating processing on the recording medium by a heating unit that is turned on by receiving power supply from a commercial power supply while passing through the image forming apparatus, and includes a temperature detector that detects a temperature of the fixing body or the heating unit. In the heating device for the apparatus, the image forming apparatus includes a power supply control unit that controls power supply from a commercial power supply to the heating unit, and the power supply control unit is configured to perform a heating operation on the fixing body or the heating unit. The power supply from the commercial power supply to the heating means in each of the temperature increasing step from the predetermined temperature taken lower than the temperature to the target temperature and the step of maintaining the fixing member or the heating means at the target temperature is P
ID control is set, and the control table for PID control in each step of the temperature raising step and the maintenance step is achieved by the first invention in which different control values are used.

Further, according to the present application, the above object is achieved in the first invention according to the present application, in which the power supply control means includes means for changing the power supply control means from a commercial power supply to a heating means for heating one sheet or one recording medium. PID control is performed for the power supply to the
The control table for the D control is also achieved by the second invention in which different control values are used.

Further, according to the present application, the above object is achieved in the first invention or the second invention according to the present application, wherein the power supply control means includes a plurality of N or N continuous recording media. The power supply from the commercial power supply to the heating means over the heating process is P
It is set so as to perform ID control, from the heating processing step of each recording medium and the heating processing of the Mth or Mth recording medium to the start of heating processing of the (M + 1) th or Mth recording medium. The control table for PID control in each of the inter-media processes is also achieved by the third invention in which different control values are used.

According to the present application, the above object is achieved by any one of the first to third inventions according to the present application.
According to the fourth invention, the control table for PID control in each of the maintenance step, the heat treatment step, and the inter-medium step is different from the control table for PID control in the temperature raising step. Achieved.

Further, according to the present application, the above object is achieved in any one of the first to fourth inventions according to the present application, wherein the fixing member is an endless belt-shaped film mainly composed of a heat-resistant material. The heating means is provided with a heating element which generates heat by supplying electric power from a commercial power supply on one surface of a thin substrate mainly composed of ceramics, and a temperature detecting member is brought into contact with or close to the other surface of the substrate. The invention is also attained by the fifth invention in which the ceramic heater is arranged in a vertical position.

Further, according to the present application, the above object is achieved by forming an image on a latent image carrier in accordance with externally provided information and then performing a heating process on a recording medium carrying the image. An apparatus, comprising: a heating device according to the first invention of the present application; and a power supply control unit that controls power supply from a commercial power supply to the heating unit, wherein the power supply control unit includes a fixing unit or a heating unit. Electric power from the commercial power supply to the heating means during each of a temperature raising step from a predetermined temperature taken lower than the target temperature for the heating treatment of the means to the target temperature and a step of maintaining the fixing member or the heating means at the target temperature. The present invention is also achieved by the sixth invention in which the supply is set to perform PID control, and the control tables for PID control in each of the temperature raising step and the maintenance step have different control values.

Further, according to the present application, the above object is achieved in the sixth invention according to the present application, in which the power supply control means includes means for changing the heating means from a commercial power supply to a heating process for one or one recording medium. PID control is performed for power supply to the power supply, and P P in each step of the temperature raising step and the heat treatment step is set.
The control table for ID control is also achieved by the seventh invention in which different control values are used.

Further, according to the present application, the above object is achieved in the sixth or seventh invention according to the present application, wherein the power supply control means is arranged to control a plurality of N or N continuous recording media. PI from the power supply from the commercial power supply to the heating means over the heating process
D control is set so that the heating process of each recording medium and the heating process of the Mth or Mth recording medium are completed until the heating process of the (M + 1) th or Mth recording medium is started. The control table for PID control in each of the inter-media processes is also achieved by the eighth invention in which different control values are used.

Further, according to the present application, the above object is achieved by any one of the sixth to eighth inventions according to the present application, wherein the PID control in each of the maintenance step, the heat treatment step and the inter-medium step is performed. Is achieved by the ninth invention that a control value different from that of the control table for PID control in the temperature raising step is adopted.

According to the present application, the above object is achieved by any one of the sixth to ninth inventions according to the present application.
The fixing body is an endless belt-shaped film mainly composed of a heat-resistant material, and the heating means is provided with a heating element that generates heat by power supply from a commercial power supply on one surface of a thin substrate mainly composed of ceramics, Further, the present invention is also achieved by a tenth invention in which the ceramic heater is a ceramic heater in which a temperature detector is placed in contact with or close to the other surface of the substrate.

Further, according to the present application, the above object is achieved in any one of the sixth to tenth inventions according to the present application, wherein the heating device performs a heating process on a recording medium carrying an unfixed image. The invention is also attained by an eleventh invention in which a fixing device for melting the unfixed image and fixing the unfixed image to the recording medium by applying the toner to the recording medium to permanently fix the unfixed image to the recording medium.

According to the present application, the above object is achieved by any one of the sixth to tenth aspects of the present invention.
The heating device is also achieved by a twelfth invention in which a heating device is configured to temporarily heat the unfixed image to the recording medium by performing a heating process on the recording medium carrying the unfixed image.

Further, according to the present application, the above object is achieved in any one of the sixth to tenth inventions according to the present application, wherein the heating device performs a heating process on the recording medium carrying the fixed image. Accordingly, the present invention is also achieved by a thirteenth invention in which a surface modification device for modifying the surface properties of the recording medium is constituted.

That is, in the first invention according to the present application, the control tables for the PID control in each of the temperature raising step and the maintenance step are set to control values different from each other. The means performs PID control of power supply from the commercial power supply to the heating means over the respective steps based on the respective control tables in the respective steps.

In the second invention according to the present application,
The control tables for the PID control in each of the temperature raising step and the heat treatment step have different control values, and the power supply control means performs control over the heat treatment step based on the control table in the heat treatment step. The power supply from the commercial power supply to the heating means is PID controlled.

Further, in the third invention according to the present application, the PI in each step of the heat treatment step and the inter-medium step is set.
The control table for the D control has different control values from each other, and the power supply control means performs continuous heating processing on a plurality of or a plurality of recording media based on the control tables in the respective steps. The power supply from the commercial power supply to the heating means is PID controlled.

Further, in the fourth invention according to the present application,
The control table for the PID control in each of the maintenance process, the heat treatment process, and the inter-medium process has a control value different from that of the control table for the PID control in the temperature increasing process, and the power supply control unit includes: PID control of power supply from the commercial power supply to the heating means in each of the steps is performed based on each control table in each of the temperature raising step, the maintenance step, the heat treatment step, and the inter-medium step.

Further, in the fifth invention according to the present application, the nip portion between the film and the pressure member pressed against each other is heated by heating the ceramic heater.

In the sixth invention according to the present application,
The control tables for the PID control in each of the temperature raising step and the maintenance step are set to different control values, and the power supply control unit performs the control over the respective steps based on the respective control tables in the respective steps. The power supply from the commercial power supply to the heating means is PID controlled.

Further, in the seventh invention according to the present application, the PID in each of the temperature raising step and the heat treatment step
The control table for the control has different control values, and the power supply control means performs PID control of the power supply from the commercial power supply to the heating means over the heating processing step based on the control table in the heating processing step. I do.

In the eighth invention according to the present application,
Control tables for PID control in each step of the heat treatment step and the inter-medium step have different control values, and the power supply control means performs recording of a plurality of sheets based on each control table in each step. PID to supply power from the commercial power supply to the heating means over the continuous heating process for the medium
Control.

Further, in the ninth invention according to the present application, a control table for PID control in each of the maintenance step, the heat treatment step and the inter-medium step is provided for controlling the PID in the temperature raising step. A control value different from that of the control table is adopted, and the power supply control unit is configured to switch from the commercial power supply for each of the steps based on the control tables in the temperature raising step, the maintenance step, the heat treatment step, and the inter-medium step. The power supply to the heating means is PID controlled.

In the tenth invention according to the present application,
The nip portion between the film and the pressure member pressed against each other is heated by the ceramic heater.

Further, according to the eleventh aspect of the present invention, while the recording medium carrying the unfixed image is passed through the nip between the fixing body and the pressing body pressed against each other, the heating means The unfixed image is melted and fixed to the recording medium by performing the heat treatment on the recording medium.

Further, in the twelfth invention according to the present application, while the recording medium carrying the unfixed image is passed through the nip between the fixing member and the pressing member pressed against each other, the heating means Then, the unfixed image is temporarily attached to the recording medium by performing the heat treatment on the recording medium.

Further, in the thirteenth invention according to the present application, while the recording medium carrying the fixed image is passed through the nip between the fixing body and the pressing body pressed against each other, the heating medium is By performing a heat treatment on the recording medium, the surface properties of the recording medium are modified.

[0038]

Embodiments of the present invention will be described with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a laser printer 1 (hereinafter, abbreviated as printer 1), which is a preferred example of the image forming apparatus according to the present embodiment.

The printer 1 is an output device (not shown) such as a host computer provided outside the main body of the printer 1.
Is an image forming apparatus that records an image corresponding to information provided from a recording medium P on a recording medium P.

The printer 1 is an image forming apparatus in which an image corresponding to information provided from an output device (not shown) such as a host computer provided outside the main body of the printer 1 is recorded on a recording medium P. .

As shown in FIG. 1, the printer 1 has a drum-shaped latent image carrier 2 that carries an electrostatic latent image on the outer peripheral surface according to information provided from an output device, and develops the electrostatic latent image. And a transfer roller 4 for transferring the developer image as an unfixed image to a recording medium P.
And a fixing device 5 for performing a fixing process on the recording medium P after the transfer process.

In the present embodiment, the latent image carrier 2 and the developing device 3 are integrally controlled by an engine controller 6 provided in the main body of the printer 1 in the present embodiment. I have.

The surface layer of the latent image carrier 2 is a photoconductive layer mainly composed of an organic photoreceptor, and receives a driving force from a driving mechanism (not shown) provided in the main body of the printer 1. Thereby, it is driven to rotate clockwise.

That is, the outer peripheral surface of the latent image carrier 2 is charged to a predetermined potential distribution by the primary charging roller 7, and then the laser La blinked from the exposure device 24 in accordance with information provided from the output device is applied to the mirror 8 or the like. By being exposed through
An electrostatic latent image corresponding to the provided information is formed.

The transfer roller 4 is rotatably supported at a position in contact with or close to the latent image carrier 2, so that the transfer nip portion TN for performing the transfer process on the recording medium P is transferred to the latent image carrier 2. 2 is formed.

That is, in this embodiment, the transfer roller 4 charges the recording medium P that has reached the transfer nip portion TN to a polarity opposite to that of the developer image on the outer peripheral surface of the latent image carrier 2. An electrical interaction is caused between the developer image and the recording medium P, so that the developer image is carried on the recording medium P as an unfixed image.

In this embodiment, the recording medium P
First, a transport roller 11 rotatably supported by a paper feed roller 10 from a cassette 9 removably supported by the main body of the printer 1 at a position upstream of the paper feed roller 10 in the recording medium transport direction. Is fed to

Next, the recording medium P that has reached the transport roller 12 is transported by the transport roller 12 to a paper feed sensor 12 that is disposed upstream of the transport roller 12 in the recording medium transport direction.
Transported to

The feed sensor 12 causes the recording medium P to transfer the recording medium P to the transfer nip TN so that the leading end of the unfixed image carrying portion on the recording medium P and the leading end of the image forming portion on the outer peripheral surface of the latent image carrier 2 are synchronized. Will be transported to

As shown in FIG. 2, the fixing device 5 includes a ceramic heater 15 (hereinafter, simply referred to as a heater 15) as a heating means, an endless belt-like film 16 as a fixing member, and a cylindrical or cylindrical member as a pressing member. A substantially cylindrical rotatable pressure roller 17, a thermistor temperature sensing element 18 for detecting the temperature of the heater 15 (hereinafter abbreviated as the thermistor 18), support of the heater 15, and movement of the film 16 in a predetermined direction. And a holder 19 also serving as a guide.

FIG. 2 is a schematic sectional view showing a schematic configuration of the fixing device 5. As shown in FIG.

As shown in FIG. 3, the heater 15 is mainly composed of a good thermal conductive ceramic such as alumina, and has a thickness = 1.
One surface of the substrate 14A taken at 0 mm has TaSiO ₂ , A
A heating element 14B mainly composed of gPd, Ta ₂ N, RuO _2, nichrome or the like and having a resistance of 34Ω is provided.
A thermistor 18 is disposed in contact with the other surface of the substrate 14A, and the one surface is coated with a protective layer 15C mainly composed of glass or fluororesin for protection from sliding contact with the film 16. ing.

FIG. 3 is a schematic sectional view showing a schematic configuration of the heater 15.

As shown in FIG. 4, the heating element 14B receives power from a commercial power supply 21 via a triac 20, and the power supply from the commercial power supply 21 to the heating element 14B is controlled by a power supply control. Central processing unit 23 as means
(Hereinafter, abbreviated as CPU 23).

FIG. 4 shows that the heating element 15 is
FIG. 4 is a schematic block diagram illustrating a power supply path to B.

That is, the heater 15 is turned on when the heating element 15B supplied with electric power from the commercial power supply 21 generates heat.

As shown in FIG. 2, the inner peripheral length of the film 16 is slightly longer than the outer peripheral length of the holder 19, so that the film 16 is fitted to the holder 19 without tension. I have.

Further, in order to reduce the heat capacity of the film 16, the present embodiment employs a single-layer structure in which the film 16 is an endless band mainly composed of polyimide.

The structure of the film 16 is not limited to this embodiment. As another effective structure for reducing the heat capacity, for example, PTFE, PFA, FEP or the like as a heat-resistant material is used as a main component. Single layer structure of endless strip, or polyimide, polyamide imide, PEE
A two-layer structure in which an outer peripheral surface of an endless band mainly composed of K, PES, PPS or the like is coated with an endless band mainly composed of PTFE, PFA, FEP, or the like.

The pressure roller 17 has a cylindrical or substantially cylindrical core bar 17A mainly composed of iron or aluminum or the like, and an outer peripheral surface thereof covered with an elastic layer 17B mainly composed of a good release silicone rubber or the like. ing.

The pressure roller 17 is configured to be pressed against the film 16 from a pressure mechanism (not shown) provided outside the fixing device 5, so that the pressure rollers 17 are pressed against each other. A nip portion N through which a recording medium P carrying an unfixed image passes is formed between the film 16 and the pressure roller 17.

Further, the pressure roller 17 is driven to rotate counterclockwise by receiving a driving force from a driving mechanism (not shown) provided outside the fixing device 5.

Therefore, while the recording medium P which has begun to enter the nip portion N is conveyed while being held by the film 16 and the pressure roller 17, the unfixed image is melted by the heating of the heater 15 and is recorded as a fixed image. It will be recorded on the medium P.

Next, the commercial power supply from the start of the ceramic heater 15 in the present embodiment to the temperature rise to the target temperature (the target temperature is set to 180 ° C. in the present embodiment). The process of controlling the power supply from 21 to the heating element 15B will be described with reference to FIGS.

FIG. 5 is a graph showing the transition of the output value from the thermistor 18 under the power supply control according to the present embodiment. The detected temperature of the thermistor 18 in the above is a temperature value T0 which is reduced to the use environment temperature or almost to the use environment temperature.

The graph of FIG. 5 shows the transition of the output of the thermistor 18 in an environment where the temperature is 23 ° C. and the humidity is 30% and the input voltage from the commercial power supply 21 to the printer 1 is 106 V. The input voltage generally fluctuates by about ± 10 V.
Since the fluctuation when the 5 V system is shared is in the range of about 35 to 40 V, a measured value obtained by providing an input voltage detection circuit for measuring the input voltage between the commercial power supply 21 and the printer 1 And

Therefore, the target temperature of the heater 15 in the fixing process (target temperature = 190 ° C. in FIG. 5) is determined according to the temperature detected by the thermistor 18 before the heater 15 is started. Can be

Accordingly, power supply from the commercial power supply 21 to the heating element 15B is performed from the commercial power supply 21 to the heating element 15B according to the detected temperature of the thermistor 18 and the rate of change of the detected temperature of the thermistor 18 before the heater 15 is started. As a result, the temperature of the heater 15 is increased to a predetermined temperature lower than the target temperature (in FIG. 5, the predetermined temperature is set to 185 ° C.).

Next, in order to prevent overshoot and undershoot in the heater 15, the heater 15
As the temperature rises to the predetermined temperature, the CPU 23 controls the power supply from the commercial power supply 21 to the heating element 15B based on the control table of FIG. 6 to raise the temperature of the heater 15 from the predetermined temperature to the target temperature. A process is performed.

FIG. 6 is a control table showing control values in the PID control in the temperature raising step.

When the temperature of the heater 15 rises to the target temperature, the CPU 23 supplies the electric power from the commercial power supply 21 to the heating element 15B based on the control table of FIG. 7 in order to maintain the heater 15 at the target temperature. By controlling the supply, a step of maintaining the heater 15 at the target temperature is performed.

FIG. 7 is a control table showing control values in the PID control in the maintenance process.

That is, in this embodiment, the CPU 23
Are set to perform power supply control in the temperature raising step based on the control table in FIG. 6 and to perform power supply control in the maintenance step based on the control table in FIG.

Here, FIG. 6 and FIG. 7 will be described in detail.

The PID control includes proportional control (hereinafter, referred to as P control), integral control (hereinafter, referred to as I control), and differential control (hereinafter, referred to as D control) output from a controlled object. This is a control in which the control value is determined by combining the values according to the values. In particular, in the present embodiment, P
Control tables for control, I control, and D control are defined for each control.

That is, in the present embodiment, the predetermined cycle = 130 msec under the P control. The amount of power supplied from the commercial power supply 21 to the heating element 15B over the period of the power supply 21 varies depending on the temperature detected by the thermistor 18 at the start of the predetermined period. And thermistor 18
Thermistor 18 when the target temperature is detected
Is determined based on a difference ΔV between the output voltage values (hereinafter, referred to as target voltage values).

In this embodiment, under the I control, the control for the P control is performed based on the difference ΔV and the integrated value of the difference between the output voltage value and the target voltage value over a predetermined period. The power supply amount over the predetermined period determined by the table is corrected.

That is, in the I control according to the present embodiment, the correction amount of the power supply amount over a predetermined cycle determined by the control table for the P control is controlled based on the difference ΔV. After the selection from the table, when the integrated value over the predetermined period reaches the integrated value T described in the control table for the I control, the power supply amount is corrected.

Further, in the present embodiment, under the D control, the power supply amount over the predetermined cycle determined by each control table for the P control and the I control is corrected based on the difference ΔV. It is supposed to.

In this embodiment, FIGS. 6 and 7
As can be seen from the comparison, the setting of the control value in the control table for the PID control in the temperature increasing step is set somewhat more loosely than the setting of the control value in the control table for the PID control in the maintaining step. ing.

That is, in the present embodiment, the control values in the control table of FIG. 6 are set to values emphasizing the reduction of overshoot in the temperature raising step, while the control values in the control table of FIG. , Is set to a value that emphasizes the reduction of the temperature ripple in the maintenance process.

In the present embodiment, the adjustment of the amount of electric power supplied from the commercial power supply 21 to the heating element 15B over a predetermined period is performed every half-wave of the AC power supply output from the commercial power supply 21. In FIG. 6 and FIG. 7, the wave number supplied to the power supply is determined based on the wave number control for selecting whether or not to supply the power to the heating element 15 </ b> B from the power supply 21. The number W corresponds to the power supply amount.

The power supplied from the commercial power supply 21 to the heating element 15B over a predetermined period is adjusted in addition to the control of the wave number, in addition to the control of the commercial power supply 2 for each half-wave of the AC power output from the commercial power supply 21.
Phase control to determine a phase range used for power supply to the heating element 15B from 1 is provided. However, since wave number control generates less noise than phase control, phase control is used to adjust the supplied power amount. Wave number control is more preferable than wave number control.

Here, the result of comparative measurement performed by the present inventor for confirming the effect in the present embodiment will be described with reference to FIGS.

FIG. 8 is a graph showing the transition of the output value from the thermistor thermosensitive element under the power supply control of the following comparative example, and shows the temperature increasing step and the maintaining step based on the control table of FIG. The power supply control performed in both steps is adopted as the comparative example, and the comparative example corresponds to the power supply control in the conventional temperature increasing step and the maintaining step.

As is clear from the comparison between FIG. 7 and FIG.
In FIG. 8, since the power supply control in the temperature raising step is performed based on the control table emphasizing the reduction of the temperature ripple in the maintenance step, a delay in reducing the overshoot at the end of the temperature raising step occurs. However, in FIG. 7 employing this embodiment, the degree of overshoot at the end of the temperature raising step is sufficiently suppressed as compared with FIG. 8, and the overshoot is rapidly reduced. ing.

Therefore, in this embodiment, the CPU 2
3 performs PID control of the power supply from the commercial power supply 21 to the heating element 15B over the respective steps based on the control tables in the respective steps of the temperature raising step and the maintaining step. Thus, it is possible to reliably reduce the overshoot in the above, and to contribute to saving of the power consumption in the heater, and to maintain the quality of the fixing property of the unfixed image on the recording medium P.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. Note that description of common parts of the present embodiment and the first embodiment will be omitted in place of FIGS.

FIG. 9 is a graph showing the transition of the output from the thermistor thermosensitive element under the power supply control according to the present embodiment. In the present embodiment, the graph is applied to a plurality of N recording media. The power supply from the start to the end of the continuous heating
The control is performed based on the ID control. The control table in the PID control in the heating process of each recording medium, and M from the end of the heating process of the Mth recording medium.
The control tables in the PID control in the inter-sheet process, which is the inter-media process up to the start of the heating process of the + 1st recording medium, are set to different control values.

The graph of FIG. 9 shows that the temperature = 23 ° C. and the humidity
30% usage environment, commercial power 21 to printer 1
Input voltage = 106V and basis weight (per unit area)
Mass of recording medium) = 64 g / m^Two Under the use of
The output transition of the mister 18 and the same as in the first embodiment.
In the case of the input voltage,
Input voltage detection circuit for measuring the input voltage during
It is assumed that the measured value is obtained by providing a road.

That is, in this embodiment, the PID control in each heat treatment step is performed based on the control table in FIG. 7, and the PID control in each sheet interval step is the control in FIG. It is based on a table.

FIG. 10 is a control table showing control values in the PID control in the sheet interval process.

Here, a control table in the PID control in the sheet interval process will be described in detail with reference to FIG.

In the sheet interval step, the M-th recording medium and the (M + 1) -th recording medium are used in order to reduce the temperature difference between the sheet passing area and the non-sheet passing area on the outer peripheral surface of the pressure roller 17. Is higher than the target temperature of the heater 15 in the heating process of the M-th recording medium by a predetermined temperature (in this embodiment, the predetermined temperature = 20 ° C.). It is taken low.)

Further, as the number of recording media subjected to the fixing process increases, the pressing roller 17 and its peripheral members (hereinafter, referred to as
It is abbreviated as a pressing body or the like. ) Is also sufficiently warmed, so that the heater 1 in each heat treatment step increases with the number of sheets.
The target temperature of No. 5 is set to decrease.

That is, in this embodiment, the target temperature of the heater 15 in the heating process of the first and second recording media is 170 ° C., and the heating process of the third to fifth recording media is performed. Target temperature of heater 15 in the process = 160 ° C.
The target temperature of the heater 15 in the heat treatment process of the sixth and seventh recording media is set to 150 ° C.

By the way, in the PID control in the sheet interval process, since the heat radiation amount from the pressurizing body is lower than the heat radiation amount in each heat treatment step, the pressurizing body is sufficiently warmed. In addition, it is necessary to maintain the temperature of the heater 15 at a target temperature for the sheet interval process.

Therefore, in the sheet interval process, when the PID control based on the control table in each heat treatment process is performed, the control value in the PID control may be somewhat rough. There is.

Therefore, in this embodiment, in each sheet interval process, as shown in FIG. 10, the control values in the control tables (see FIG. 7) in each heat treatment process are finer. PID control is performed based on the control table.

Here, the results of comparative measurement performed by the inventor for confirming the effect of the present embodiment will be described with reference to FIGS. 9 and 11.

FIG. 11 is a graph showing the transition of the output value from the thermistor thermosensitive element under the power supply control of the following comparative example. The power supply control performed in both of the steps is employed as the comparative example, and the comparative example corresponds to the conventional power supply control in the heat treatment step and the sheet interval step.

As is clear from the comparison between FIG. 9 and FIG. 11, in FIG. 11, the power supply control in the sheet interval process is performed based on a control table emphasizing the reduction of the temperature ripple in the heating process. For this reason, there is a delay in reducing the temperature ripple at the start of the sheet interval process. However, in FIG. 9 adopting the present embodiment, the degree of occurrence of the temperature ripple at the start of the sheet interval process is smaller than that in FIG. In addition to being sufficiently suppressed, the temperature ripple at the start of the sheet interval process is rapidly reduced.

Therefore, in the present embodiment, the control tables for the PID control in each of the heat treatment step and the sheet interval step have different control values.
The CPU 23 performs PID control of the power supply from the commercial power supply 21 to the heating element 15B over the continuous heating process on a plurality of recording media based on each control table in each of the above steps. It is possible to surely achieve both the reduction of the temperature ripple in the processing step.

The numerical values in the first and second embodiments are merely examples for simplifying the description of the first and second embodiments.
Needless to say, it is determined according to the configuration and setting of the apparatus.

Further, in the first and second embodiments, the fixing device as an example of the heating device has been adopted. However, the fixing device and the surface reforming device as other examples of the heating device are used. It goes without saying that the same effects and advantages as those of the first embodiment and the second embodiment can be obtained by employing the first embodiment and the second embodiment.

Further, in this embodiment, a laser beam printer has been adopted as a specific example of the image forming apparatus in the first embodiment and the second embodiment. For example, by applying the first embodiment and the second embodiment to an image display device and a recording machine such as a copier, a copier, a facsimile, a micro film reader printer, a display, and the like, the first embodiment and It goes without saying that the effects and advantages of the second embodiment can be obtained.

[0109]

As described above, according to the first aspect of the present invention, the control tables for the PID control in each of the temperature raising step and the maintenance step have different control values. Since the power supply control means performs PID control of the power supply from the commercial power supply to the heating means over the respective steps based on the control tables at the respective steps, the temperature ripple and the temperature increase in the maintenance step It is possible to reliably achieve both reduction of overshoot in the process.

Further, according to the second invention of the present application, the control tables for PID control in each of the temperature raising step and the heat treatment step are set to different control values from each other. The control means performs PID control of the power supply from the commercial power supply to the heating means during the heat treatment step based on the control table in the heat treatment step. Both can be surely achieved.

Further, according to the third invention of the present application,
Control tables for PID control in each step of the heat treatment step and the inter-medium step have different control values, and the power supply control means performs recording of a plurality of sheets based on each control table in each step. PID to supply power from the commercial power supply to the heating means over the continuous heating process for the medium
Since the control is performed, it is possible to reliably achieve both the reduction of the temperature ripple in the inter-media process and the reduction of the overshoot in the temperature raising process.

Further, according to the fourth invention of the present application, the control table for PID control in each of the maintenance step, the heat treatment step, and the inter-medium step has a control table for PID control in the temperature raising step. The control value is different from that of the control table, and the power supply control means performs the temperature increasing step, the maintaining step,
The PID control of the power supply from the commercial power supply to the heating means over the respective steps is performed based on the control tables in the respective steps of the heating step and the inter-medium step. Thus, it is possible to reliably achieve both the temperature ripple in the above and the reduction of the overshoot in the temperature raising step.

Furthermore, according to the fifth invention of the present application,
Since the nip portion between the film and the pressure body pressed against each other is heated by the heating of the ceramic heater,
The period from when the ceramic heater is started to when the temperature rises to the target temperature can be shortened.

According to the sixth aspect of the present invention, the control tables for the PID control in each of the temperature raising step and the maintenance step are set to different control values, and the power supply control The means performs PID control of the power supply from the commercial power supply to the heating means in each of the steps based on each control table in each of the steps, so that it is possible to reduce both the temperature ripple in the maintenance step and the overshoot in the temperature raising step. Can be provided.

Further, according to the seventh invention of the present application,
Control tables for PID control in each step of the temperature raising step and the heat treatment step have different control values, and the power supply control means performs the heat treatment step based on the control table in the heat treatment step. PID control of the power supply from the commercial power supply to the heating means over
It is possible to provide an image forming apparatus in which both temperature ripple in the heat treatment step and reduction of overshoot in the temperature raising step are reliably achieved.

Further, according to the eighth aspect of the present invention, the control tables for PID control in each of the heat treatment step and the inter-medium step have different control values, and the power supply The control means performs PID control of power supply from the commercial power supply to the heating means over a continuous heating process on a plurality of recording media based on each control table in each of the processes, so that the temperature ripple and the temperature increase in the process between the media are performed. It is possible to provide an image forming apparatus in which both reduction of overshoot in the process is surely achieved.

Further, according to the ninth invention of the present application,
The control table for the PID control in each of the maintenance process, the heat treatment process, and the inter-medium process has a control value different from that of the control table for the PID control in the temperature increasing process, and the power supply control unit includes: Based on PID control of the power supply from the commercial power supply to the heating means over the respective steps based on the control tables in the respective steps of the temperature raising step, the maintaining step, the heat treatment step, and the inter-medium step,
It is possible to provide an image forming apparatus in which a reduction in temperature ripple in each of the heat treatment step and the inter-medium step and a reduction in overshoot in the temperature raising step are reliably achieved.

Further, according to the tenth aspect of the present invention, the nip portion between the film and the pressure member pressed against each other is heated by the ceramic heater, so that the ceramic heater is started. It is possible to provide an image forming apparatus including a heating device in which the period from when the temperature is raised to the target temperature is shortened.

Further, according to the eleventh aspect of the present invention, while the recording medium carrying the unfixed image is passed through the nip between the fixing body and the pressing body pressed against each other, the heating means Since the unfixed image is melted and fixed to the recording medium by performing a heating process on the recording medium, it is possible to provide an image forming apparatus including a fixing device capable of providing high-quality fixing properties. it can.

According to the twelfth invention of the present application,
While the recording medium carrying the unfixed image is passed through the nip portion between the fixing body and the pressure body pressed against each other, by performing a heat treatment on the recording medium from a heating unit,
Since the unfixed image is hypothetically deposited on the recording medium, it is possible to provide an image forming apparatus including a hypothetical deposition apparatus that can provide high quality hypothetical deposition.

Further, according to the thirteenth aspect of the present invention, while the recording medium carrying the fixed image is passed through the nip between the fixing member and the pressing member pressed against each other, the heating medium is supplied from the heating means. By performing the heat treatment on the recording medium, the surface property of the recording medium is modified, so that it is possible to provide an image forming apparatus including a surface modifying device capable of providing high-quality surface properties.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present application.

FIG. 2 is a schematic sectional view showing a schematic configuration of the fixing device of FIG.

FIG. 3 is a schematic sectional view showing a schematic configuration of the ceramic heater of FIG. 2;

FIG. 4 is a schematic block diagram showing a power supply path from a commercial power supply to the ceramic heater of FIG. 2;

FIG. 5 is a graph showing an output transition from a thermistor thermosensitive element under power supply control according to the first embodiment of the present application.

FIG. 6 is a control table showing control values in PID control in a temperature raising step according to the first embodiment of the present application.

FIG. 7 is a control table showing control values in PID control in a maintenance process according to the first embodiment of the present application.

FIG. 8 is a graph showing a transition of an output value from a thermistor thermosensitive element under power supply control of a comparative example with respect to the first embodiment of the present application.

FIG. 9 is a graph showing an output transition from a thermistor thermosensitive element under power supply control according to the second embodiment of the present application.

FIG. 10 is a control table showing control values in PID control in a process between media according to a second embodiment of the present application.

FIG. 11 is a graph showing a transition of an output value from a thermistor thermosensitive element under power supply control of a comparative example with respect to the second embodiment of the present application.

[Explanation of symbols]

 Reference Signs List 1 laser printer (image forming apparatus) 5 fixing device 15 ceramic heater (heating means) 16 film (fixing member) 17 pressure roller (pressing member) 18 thermistor temperature sensing element (temperature detecting member) 19 holder 20 triac 21 commercial power supply Reference Signs List 22 analog-digital conversion circuit 23 central processing unit (power supply control means) 15A substrate 15B heating element 15C protective layer

Claims (13)

[Claims] An illumination device receives power from a commercial power supply while allowing a recording medium carrying an unfixed image or a fixed image to pass through a nip formed between a fixing member and a pressing member pressed against each other. A heating device for performing a heating process on the recording medium by a heating unit that performs a heating process for the image forming apparatus, the image forming device including a temperature detector that detects a temperature of the fixing body or the heating unit. And a power supply control unit for controlling power supply to the heating unit, wherein the power supply control unit raises the temperature from a predetermined temperature taken lower than a target temperature for the heat treatment of the fixing body or the heating unit to the target temperature. The power supply from the commercial power supply to the heating means is set to PID control over the process and the process of maintaining the fixing member or the heating means at the target temperature. Wherein the control table for the PID control is different in control value from each other. 2. The power supply control means is set so as to perform PID control of power supply from a commercial power supply to the heating means over the heating processing step of one or one recording medium. 2. The heating apparatus according to claim 1, wherein the control tables for the PID control in each of the steps have different control values. 3. The power supply control means is set to perform PID control of power supply from a commercial power supply to the heating means over a continuous heating process on a plurality of N or N recording media. For the PID control in each step of the heat treatment process and the inter-media process from the end of the heat treatment of the Mth or Mth recording medium to the start of the heat treatment of the (M + 1) th or Mth recording medium. 3. The heating device according to claim 1, wherein the control tables have different control values. 4. A control table for PID control in each of a maintenance process, a heat treatment process, and a process between media,
The heating device according to any one of claims 1 to 3, wherein a control value different from a control table for PID control in the temperature raising step is adopted. 5. The fixing member is an endless belt-shaped film mainly composed of a heat-resistant material, and the heating means generates heat generated by supplying power from a commercial power supply to one surface of a thin substrate mainly composed of ceramics. The heating device according to any one of claims 1 to 4, wherein the heating device is a ceramic heater provided with a body, and a temperature detection body is disposed in contact with or close to the other surface of the substrate. 6. An image forming apparatus for forming an image in accordance with externally provided information on a latent image carrier, and then subjecting the latent image carrier to a heating process on a recording medium carrying the image.
And a power supply control means for controlling power supply from a commercial power supply to the heating means, wherein the power supply control means is taken lower than a target temperature for the heat treatment of the fixing body or the heating means. The power supply from the commercial power supply to the heating means over the respective steps of a temperature raising step from the predetermined temperature to the target temperature and a step of maintaining the fixing body or the heating means at the target temperature is set so as to perform PID control. An image forming apparatus, wherein control tables for PID control in each of a process and a maintenance process have different control values. 7. The power supply control means is set so as to perform PID control of power supply from a commercial power supply to the heating means over the heating processing step of one or one recording medium. 7. The image forming apparatus according to claim 6, wherein the control tables for the PID control in each of the steps are different control values. 8. The power supply control means is set to perform PID control of power supply from a commercial power supply to the heating means over a continuous heating process on a plurality of N or N recording media. For the PID control in each step of the heat treatment process and the inter-media process from the end of the heat treatment of the Mth or Mth recording medium to the start of the heat treatment of the (M + 1) th or Mth recording medium. 8. The image forming apparatus according to claim 6, wherein the control tables have different control values. 9. A control table for PID control in each of a maintenance process, a heat treatment process, and a process between media,
9. The image forming apparatus according to claim 6, wherein a control value different from a control table for PID control in the temperature raising step is adopted. 10. The fixing body is an endless belt-shaped film mainly composed of a heat-resistant material, and the heating means generates heat generated by supplying power from a commercial power supply to one surface of a thin substrate mainly composed of ceramics. The image forming apparatus according to any one of claims 6 to 9, wherein the image forming apparatus is a ceramic heater provided with a body, and a temperature detector is arranged in contact with or close to the other surface of the substrate. . 11. A fixing device for applying heat treatment to a recording medium carrying an unfixed image to melt the unfixed image and to fix the unfixed image to the recording medium, thereby fixing the unfixed image to the recording medium permanently. The image forming apparatus according to any one of claims 6 to 10, wherein the image forming apparatus constitutes an apparatus. 12. The heating device according to claim 6, wherein the heating device performs a heating process on the recording medium carrying the unfixed image to temporarily fix the unfixed image to the recording medium. Item 11. The image forming apparatus according to any one of items 10. 13. The heating device according to claim 6, wherein the heating device performs a heating process on the recording medium carrying the fixed image to improve a surface property of the recording medium.
The image forming apparatus according to claim 10.